It is becoming common practice to use a type of fuse for motor vehicle electrical systems which comprises spaced-apart parallel coplanar blades that extend from one end of an insulating body. The blades have extensions which are supported in the insulating body and the fuse metal link extends between these extensions.
The specifications for fuses of the type described above concern only the dimensions of the fuse and its electrical characteristics. The specifications permit the manufacture of such fuses by different manufacturing methods. At present, most fuses of the type under consideration are produced by stamping and forming flat sheet metal, the fuse metal link being integral with the blades and the extensions of the blades. The insulating bodies of presently used fuses are separately molded and the metallic parts of the fuse and the body are designed such that the metallic parts can be assembled to the insulating body after the two separate parts are produced.
There have been some problems in the manufacture of fuses of the type described above with regard to controlling the amperage at which the fuseable link will melt or fail, resulting in difficulties in maintaining the tolerance limits for the fuses. When the fuse metal link is produced as part of the blades and the blade extensions, it is necessary carefully to control the cross-sectional dimensions and the length of the link thereby to control the rating of the fuse and it has been found to be difficult to maintain precise control of the rating in the stamping and forming operations. The present invention is directed to the achievement of a fuse of simplified construction and which can be manufactured in a way such that precise quality control can be maintained. The invention if further directed to the achievement of a manufacturing method for a fuse which will avoid the necessity of assembling the metallic parts of the fuse to a molded housing.
An electrical fuse in accordance with the invention comprises a pair of parallel spaced-apart conductors, each of the conductors having a supported portion and a flat blade portion. The supported portions are supported in an insulating body with the blade portions extending from one end of the insulating body. A fuse metal link has its ends connected to the supported portions and is at least partially contained in the insulating body. A fuse in accordance with the invention is particularly characterized in that the spaced-apart conductors are of die cast metal and the insulating body is molded on the spaced-apart conductors.
In accordance with further embodiments, the fuse metal link is contained in the supported portions of the conductors and the conductors are die cast onto the fuse metal link. In accordance with a further embodiment, the supported portions of the conductors are crimped onto the ends of the fuse metal link and the insulating body has an opening extending therethrough and through which the fuse metal link extends so that it is exposed.
In accordance with a further aspect of the invention, a method of producing fuses as described above is particularly characterized in that the fuse metal link is positioned in the die casting die having side-by-side mold cavities which, when filled, will produce the spaced-apart conductors of the fuse. The fuse metal link is located in the die with its ends disposed in the portions of the cavities which produce the supported portions of the conductors and with an intermediate portion of the fuse metal link extending between the cavities. The method is characterized by the further steps of injecting die castable metal into the die cavities and thereafter removing the die cast conductors from the die with the fuseable link extending between the conductors. The insulating body is thereafter molded onto the supported portions of the conductors.